Universidade Federal do Cariri
Document summarization is a task to shorten texts into concise and informative summaries. This paper introduces a novel dataset designed for summarizing multiple scientific articles into a section of a survey. Our contributions are: (1) SurveySum, a new dataset addressing the gap in domain-specific summarization tools; (2) two specific pipelines to summarize scientific articles into a section of a survey; and (3) the evaluation of these pipelines using multiple metrics to compare their performance. Our results highlight the importance of high-quality retrieval stages and the impact of different configurations on the quality of generated summaries.
Quati introduces a Brazilian Portuguese information retrieval dataset, featuring queries and a corpus developed by native speakers, and leveraging large language models for cost-effective relevance annotation. The dataset provides a robust benchmark for evaluating retrieval systems, with `BM25 + mT5-XL` achieving an nDCG@10 of 0.7109 on the larger corpus.
This work presents and investigates novel traversable wormhole solutions within the framework of Asymptotically Safe Gravity (ASG), sourced by a dark matter halo modeled by the Dekel--Zhao density profile. The scale-dependent gravitational coupling G(k)G(k), derived from the ASG renormalization group flow in the infrared regime, is incorporated directly into the field equations, providing a consistent description of quantum gravitational corrections even at astrophysical scales. The combined effects of the running coupling (parameterized by ξ\xi) and the dark matter characteristics determine the geometric structure and physical viability of the wormhole. The solutions satisfy the flare-out and asymptotic flatness conditions within restricted parameter domains, exhibiting enhanced curvature near the throat due to ASG corrections. Null Energy Conditions are necessarily violated at the throat, and stability analysis based on the adiabatic sound speed as well as the modified Tolman--Oppenheimer--Volkoff equation reveal that quantum effects from ASG counteract the destabilizing influence of dark matter. Phenomenologically, the wormhole shadow radius increases nearly linearly with ξ\xi, lying within the Event Horizon Telescope bounds for Sgr~A^* when ξ/M0.80.9\xi/M \simeq 0.8--0.9, thus suggesting that ASG-corrected wormholes may represent observable signatures of quantum gravity in the strong-field regime.
The phenomena where a quantum system can be exponentially accelerated to its stationary state has been refereed to as Quantum Mpemba Effect (QMpE). Due to its analogy with the classical Mpemba effect, hot water freezes faster than cold water, this phenomena has garnered significant attention. Although QMpE has been characterized and experimentally verified in different scenarios, sufficient and necessary conditions to achieve such a phenomenon are still under investigation. In this paper we address a sufficient condition for QMpE through a general approach for open quantum systems dynamics. With help of the Mpemba parameter introduced in this work to quantify how strong the QMpE can be, we discuss how our conditions can predict and explain the emergence of weak and strong QMpE in a robust way. As application, by harnessing intrinsic non-classical nature of squeezed thermal environments, we show how strong QMpE can be effectively induced when our conditions are met. Due to the thermal nature of environment considered in our model, our work demonstrates that a hot qubit freezes faster than a cold qubit only in presence of squeezed reservoirs. Our results provide tools and new insights opening a broad avenue for further investigation at most fundamental levels of this peculiar phenomena in the quantum realm.
The Dymnikova black hole (BH) is a regular solution that interpolates between a de Sitter core near the origin and a Schwarzschild-like behavior at large distances. In this work, we investigate the properties of a Dymnikova BH immersed in a quintessential field, characterized by the state parameter ω\omega and a normalization constant cc. We explore the thermodynamic behavior, null geodesics, scalar quasinormal modes and shadow profiles for this model. Our analysis shows that the presence of quintessence alters the Hawking temperature and specific heat, leading to parameter-dependent phase transitions. The null geodesics and corresponding black hole shadows are also found to be sensitive to the model parameters, especially ω\omega and cc. This sensitivity influences light deflection and shadow size. Furthermore, we compute the scalar quasinormal modes and observe that quintessence tends to enhance the damping of the modes, indicating greater stability under perturbations.
The decline in interest rates and economic stabilization has heightened the importance of accurate mortality rate forecasting, particularly in insurance and pension markets. Multi-step-ahead predictions are crucial for public health, demographic planning, and insurance risk assessments; however, they face challenges when data are limited. Hybrid systems that combine statistical and Machine Learning (ML) models offer a promising solution for handling both linear and nonlinear patterns. This study evaluated the impact of different multi-step forecasting approaches (Recursive, Direct, and Multi-Input Multi-Output) and ML models on the accuracy of hybrid systems. Results from 12 datasets and 21 models show that the selection of both the multi-step approach and the ML model is essential for improving performance, with the ARIMA-LSTM hybrid using a recursive approach outperforming other models in most cases.
We study the properties of an electron on a catenoid surface. The catenoid is understood as a realization of a bridge connecting two graphene layer by a smooth surface. The curvature induces a symmetrical reflectionless potential well around the bridge with one bound-state for m=0m=0. For m0m\neq 0, a centrifugal potential barrier arises controlling the tunnelling between the layers. An external electric field breaks the parity symmetry and provides a barrier that controls the conductance from one layer to another. By applying a constant magnetic field the effective potential exhibits a confining double-well potential nearby the bridge. We obtain the corresponding bound states and study the effects of the curvature on the Landau levels.
There has been a growing interest within the astrophysics community in highly magnetized and fast-spinning white dwarfs (WDs), commonly referred to as HMWDs. WDs with these characteristics are quite uncommon and possess magnetic fields 106\geqslant 10^6 G, along with short rotation periods ranging from seconds to just a few minutes. Based on our previous work, we analyze the emission of Gravitational Waves (GWs) in HMWDs through two mechanisms: matter accretion and magnetic deformation, which arise due to the asymmetry surrounding the star's rotational axis. Here, we perform a thorough self-consistent analysis, accounting for rotation and employing a realistic equation of state to investigate the stability of stars. Our investigation focuses on the emission of gravitational radiation from six rapidly spinning WDs: five of them are situated within binary systems, while one is an AXP, proposed as a magnetic accreting WD. Furthermore, we apply the matter accretion mechanism alongside the magnetic deformation mechanism to assess the influence of one process on the other. Our discoveries indicate that these WDs could potentially act as GW sources for BBO and DECIGO, depending on specific parameters, such as their mass, the angle (α\alpha) between the magnetic and rotational axes, and the accumulated mass (δm\delta m) at their magnetic poles, which is influenced by the effect of matter accretion. However, detecting this particular class of stars using the LISA and TianQin space detectors seems unlikely due to the challenging combination of parameters such as a large δm\delta m, a large α\alpha angle and a small WD mass value.
In this work, we explore the strain and curvature effects on the electronic properties of a curved graphene structure, called the graphene wormhole. The electron dynamics is described by a massless Dirac fermion containing position--dependent Fermi velocity. In addition, the strain produces a pseudo--magnetic vector potential to the geometric coupling. For an isotropic strain tensor, the decoupled components of the spinor field exhibit a supersymmetric (SUSY) potential, depending on the centrifugal term and the external magnetic field only. In the absence of a external magnetic field, the strain yields to an exponential damped amplitude, whereas the curvature leads to a power--law damping of the wave function. The spin--curvature coupling breaks the chiral symmetry between the upper and the lower spinor component, which leads to the increasing of the wave function on either upper or lower region of the wormhole, i.e., depending on the spin number. By adding an uniform magnetic field, the effective potential exhibits an asymptotic quadratic profile and a spin--curvature barrier near the throat. As a result, the bound states (Landau levels) are confined around the wormhole throat showing an asymmetric and spin--dependent profile.
In this paper we study black string solutions considering the Lifshitz anisotropic scaling. We have shown that a new class of asymptotically Lifshitz solutions can be generated by an Einstein-Maxwell-Dilaton theory with a cosmological constant. In the limit where we recover conformal scale invariance, we retrieve the usual black string solution. Furthermore, we demonstrated that to incorporate the effects of electric charge in the black string, at least two independent gauge fields coupled to the dilaton field are necessary. The charged black string solution exhibits new horizons that depend on the potential in Lifshitz exponent zz. The stability of these new solutions is investigated through the thermodynamic analysis of the charged black string. The temperature, entropy, and heat capacity indicate that these modified black strings are thermodynamically stable.
In this paper we investigate the arising of non-hermitian phase transitions on quantum torus surfaces. We consider a single fermion whose dynamics is governed by the Dirac equation confined to move on a quantum torus surface. The effects of the geometry are take into account by using the tetrad formalism and the spin connection. The Dirac equation gives rise to two coupled first-order differential equations for each spinor component. The eigenvalues and eigenfunctions for each spinor component are computed numerically and the non-hermitian phase transitions are investigated in terms of the geometric features of the torus and the magnitude of the imaginary component of the mass.
We investigated the effects of the spacetime curvature and extra dimensions on the excitations of a self-interacting vector field known as the bumblebee field. The self-interacting quadratic potential breaks the gauge invariance and the vacuum expectation value (VEV) of the bumblebee field bMb_M violates the local particle Lorentz symmetry. By assuming the bumblebee field living in a AdS5AdS_{5} bulk, we found an exponential suppression of the self-interacting constant λ\lambda and the bumblebee VEV along the extra dimension. The fluctuations of the bumblebee upon the VEV can be decomposed into transverse and longitudinal modes with respect to bMb_{M}. Despite the curvature, the transverse mode acquires massive Kaluza-Klein towers, while the longitudinal mode acquires LV mass λb2\lambda b^{2}. On the other hand, the current conservation law prevents massive Kaluza-Klein modes for the longitudinal mode. For a spacelike bMb_{M} along the extra dimension and assuming a FRW 3-brane embedded in the AdS5AdS_{5} yields to an additional dissipative term to the longitudinal mode. The cosmological expansion leads to decay of the longitudinal mode in a time ΔtH1\Delta t \approx H^{-1}, where H=a˙/aH=\dot{a}/a is the Hubble parameter and a(t)a(t) is the scale factor. For a timelike bMb_{M}, the longitudinal mode does not propagate on the brane and its amplitude decays in time with a3a^{-3} and in the extra dimension with zλb2l2z^{-\lambda b^{2}l^{2}}.
In this paper, we investigate the influence of the geometry in the electronic states of a quantum ripple surface. We have considered an electron governed by the spinless stationary Schrödinger equation constrained to move on the ripple surface due to a confining potential from which the Da Costa potential emerges. We investigate the role played by the geometry and orbital angular momentum on the electronic states of the system.
In this paper, we investigate the emergence of non-Hermitian phase transitions on a quantum wormhole surface. We consider a single fermion whose dynamics are governed by the Dirac equation confined to move on a quantum wormhole surface. The effects of the geometry are taken into account using the tetrad formalism and the spin connection. The Dirac equation gives rise to two coupled first-order differential equations for each spinor component. The eigenvalues and eigenfunctions for each spinor component are computed numerically, and the non-Hermitian phase transitions are investigated in terms of the geometric features of the wormhole and the magnitude of the imaginary component of the mass.
We studied a Lorentz-violating inspired Ginzburg-Landau model for superconductivity where we considered a CPT-odd contribution given by (kAF)μ(k_{AF})^{\mu}, also known as the Carroll-Field-Jackiw term. In the static limit of the equations, we could find a pair of modified Ginzburg-Landau equations. Furthermore, these equations were reduced to the London equation for the magnetic field when assumed that the characteristic length of the order parameter is much smaller than the characteristic length of the magnetic field, i.e. the London penetration length. Our numerical solutions showed a simple Meissner state when this new term is small compared to λL\lambda_L and a phase transition into phases with strong in-plane currents and anomalous vortices for large contributions. This model becomes useful in exemplifying the changes in the phenomenology of superconductors when the setup of the system shows an important breakdown of Lorentz invariance. Based on these results, we discuss how such models might be the hallmark of unusual superconducting states where there is a direction where the system shows stratification, as in anapole superconductors UTe2_2.
We present anomaly-free solutions suitable for an inverse seesaw realization within a U(1)BLU(1)_{B-L} extension. Implementing such a mechanism, in a phenomenologically viable way, requires the inclusion of at least four exotic fermions, assumed to be Standard Model singlets. In order to build anomaly-free models, the BLB-L charges of these exotic fermions must satisfy two constraint equations, known as the anomaly equations. Here, we focus on solutions involving four to eight new right-handed fermions, favoring cases where all the BLB-L charges of these fermions are rational numbers. We showed that, when considering only the right-handed fermions necessary to realize the mechanism, the solutions must have irrational charge values. By adding one more exotic singlet fermion, which does not directly enter the mechanism mass matrix, it becomes possible to find solutions with rational charges, while the addition of a second one enables a reduction of the scalar sector. On top of the two anomaly equations, a set of inequalities and additional constraint equations were added to correctly account for neutrino masses and to minimize the scalar content. So here we present sets of charges that obey the anomaly equations as well as these additional constraints. Finally, we explore the phenomenological implications of such solutions by analyzing their capacity to provide a framework for dark matter candidates, choosing one particular solution as an example.
In this paper, we study the polymer black hole solution surrounded by a quintessence field. The influence of quintessence on the polymer black hole is investigated through its thermodynamic properties, such as the Hawking temperature, entropy, and specific heat, which allow us to address the question of thermodynamic stability. We then calculate bounds on the electromagnetic greybody factors and photon emission rates of the black hole, highlighting the interplay between quintessence and quantum gravity effects in determining these phenomena. We also examine the effects of quintessence and quantum gravity on the geodesics and shadows of massless particles around the black hole. Our results are further compared with observational data of the Sagittarius A black hole from the Event Horizon Telescope (EHT) collaboration.
In this work, we investigate the relativistic structure of white dwarfs (WDs) within the framework of modified gravity theory f(R,T,Lm)=R+αTLmf(R, T, L_m) = R + \alpha T L_m, which introduces a non-minimal coupling between matter and curvature. Using a realistic equation of state (EoS) that includes contributions from a relativistic degenerate electron gas and ionic lattice effects, we solve the modified Tolman-Oppenheimer-Volkoff (TOV) equations for two standard choices of the matter Lagrangian density: Lm=pL_m = p and Lm=ρL_m = -\rho. We show that the extra αTLm\alpha TL_m term significantly alters the mass-radius relation of WDs, especially at high central densities (ρc108109g/cm3)( \rho_c \gtrsim 10^8 - 10^9\,\rm g/cm^3), allowing for stable super-Chandrasekhar configurations. In particular, depending on the sign and magnitude of the parameter α\alpha, the maximum mass can increase or decrease, and in some regimes, the usual critical point indicating the transition from stability to instability disappears. Our findings suggest that f(R,T,Lm)f(R,T,L_m) gravity provides a viable framework to explain the existence of massive WDs beyond the classical Chandrasekhar limit.
In this paper, we study the charged and uncharged BTZ counterpart of the Black-Bounce proposed by Simpson and Visser recently. For the uncharged case, we find that the temperature is not modified by the bounce parameter. We also find that the wormhole side of the solution must always be supported by exotic matter over the throat. For the charged case we find that the thermodynamics is changed and the bounce parameter controls a phase transition, affecting the sign of the heat capacity and therefore the stability of the system. For the uncharged case, we find that there are no stable orbits for both massive and massless incoming particles while stable orbits are present for the charged case and the bounce parameter affects the points of stability.
In this work, a regular black string solution will be presented from the method used by Simpson-Visser to regularize the Schwarzschild solution. As in the Simpson-Visser work, in this new black string solution, it is possible to represent both a regular black hole and a wormhole just by changing the value of a parameter "aa" used in its metric. Tensors and curvature invariants were analyzed to verify the regularity of the solution, as well as the energy conditions of the system. It was found that the null energy condition will always be violated for the entire space. The analysis of the thermodynamic properties of the regular black string was also carried out, in which the modifications generated about the original solution of the black string, were evaluated, specifically, the Hawking temperature, entropy, its thermal capacity, and the Helmholtz free energy. Finally, we investigate the possible stable or unstable circular orbits for photons and massive particles. The results were compared with those of the non-regular black string, seeking to make a parallel with the Simpson-Visser work.
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